For most turbochargers, axial clearances between rotating assembly components affects lubricant flow requirements and performance. Such clearances change with respect to temperature, especially as a turbocharger cycles between ambient temperatures (e.g., “cold start” temperatures) and operating temperatures. As components of different materials expand and contract, clearance ratios change. For example, a brass bearing with a length of about 30 mm will expand more than a steel shaft section seated in the bearing. In such a scenario, clearances between the brass bearing and facing components are likely to decrease with increasing temperature. Where such clearances are required for adequate lubricant flow, such flow may be adversely affected as operating temperature increases. Where the lubricant aims to cool components of a rotating assembly, any decrease in flow is generally undesirable.
Various conventional bearings are unitary (e.g., machined plain brass bearings). Such unitary, machined bearings are associated with some significant limitations as to features. Various exemplary multi-piece bearings described herein can reduce clearance-related thermal expansion issues and more readily allow for features that can benefit turbocharger performance.